Hey,
I produced a file which always crashes TG2 immediately when you (or the program itself) enable True Lighting in the 3D preview.
It's attached to this post.
edit: attached a different version that doesn't require the external heightfield
Just to confirm, I dl'd your file and it crashes on my system too.
Richard
This can happen if certain nodes are used as blend shaders or in some other situations where they modify the colour of a surface. These bugs have been fixed for the next update. You should be able to identiy the particular shader to blame in this project by disabling all shaders and then re-enabling them until the crash occurs.
Matt